I have few
computers on Exchange ActiveSync and some of them stop
updating folders. After short investigation I realized that
outlook is stuck on Calendar Update and it do not update
rest of the folders anymore. I can send emails but I do not
receive anything.

I found work
around. I have to login to user account on web mail, create
temporary folder and move all calendar events to new
folders. And then move them back one by one. During this
process outlook can stuck again so I have to move few events
back to temporary folder, restart outlook at least twice and
start moving events back to original calendar folder again.